In continuous ink jet printing, a conductive, preferably aqueous based fluid is forced through a restriction at a relatively high pressure, creating a fine stream of liquid which is then broken into droplets. The resulting stream of droplets is selectably electrically charged and subsequently selectably deflected by a deflection electrode, so as to direct the droplet either to a target on a substrate to be marked or to a droplet collector.
In the prior art there are known porous deflection electrodes formed of vitreous carbon or stainless steel which allow any fluid to wick into the electrode for removal later in a printing cycle by vacuum. Such electrodes are quite brittle and have a relatively low production yield.
Deflection electrodes formed of sintered steel which is post treated at high temperatures are also known but suffer from non-uniform porosity.
The following U.S. Patents describe various electrode configurations useful in fluid jet printing: U.S. Pat. Nos. 4,307,407; 4,651,163; 4,658,269 and 4,839,664.